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Virtual Cable™ Safety
The Virtual Cable™ is the only route guidance display that allows the driver to keep eyes on the road, hands on the wheel and mind on driving at all times.
Only the driver's peripheral vision is needed to follow the Virtual Cable™. The driver does not have to interpret audio commands or translate map symbology.
Current navigation systems are inherently unsafe. They require either the reading and interpreting map data or the comprehension and interpretation of audio commands describing the road ahead. These activities require time and divert the driver's attention away from the road ahead.
Government-sponsored safety studies have shown that head-up display (HUD) based navigation can be much safer and more effective than any other route-guidance method; if and only if:
- the image is simple;
- it is presented above the driver's line of sight;
- it is perceived be to be a stationary and real part of the landscape;
The Virtual Cable™ is the only image form that meets all 3 of these criteria.
The Virtual Cable™ interface can also be used in other automotive safety-related applications: road-departure accident prevention, dynamic maximum speed control, tailgating avoidance and collision avoidance.
Government Sponsored Safety Studies
Numerous accident causation studies have concluded that driver distraction is the most common contributing factor in traffic accidents.
Car navigation systems commonly used today are necessarily distracting and therefore unsafe:
- Studies show that an average middle-aged driver needs 5 seconds (each time) to read and interpret the map display of a typical navigation system. The maximum safe time limit for such activity has been determined to be 2 seconds.
- Voice-command navigation systems can be just as unsafe as the screen-based systems. They require the driver to frequently switch between visual and auditory perception, which most people find distracting. Having to look for and then read street names and road signs also diverts the driver's attention from the road ahead.
- The existing car navigation systems have been shown to be particularly unsafe for older drivers, who (because of their impaired memory and vision) could benefit the most from a safe and practical car navigation system.
HUD Safety Studies
Addressing these concerns, the industry is interested in head-up display (HUD) technology, which has been proven successful in aircraft applications. Studies have shown that automotive HUDs are safer than the instrument-panel displays, especially for older drivers (see "Human Factors Aspects of Using Head Up Displays in Automobiles: A Review of the Literature" - Kenneth W. Gish and Loren Staplin, a study sponsored by the US NHTSA).
Many of these studies were conducted more than a decade ago, yet automotive HUDs still have not been a commercial success. The existing HUD designs do not offer improvements significant enough to justify the cost.
Studies sponsored by National Aeronautics and Space Administration (NASA) has shown significant flaws in the current HUD designs. These flaws make the existing automotive HUDs only marginally safer and more effective than the traditional displays and likely account for the lack of popular acceptance of these systems.
The Virtual Cable™ is the only automotive HUD that does not have any of the safety design flaws pointed out by these studies.
Accident Causation Studies - References
- "The Relative Frequency Of Unsafe Driving Acts In Serious Traffic Crashes" - D. L. Hendricks, J. C. Fell and M. Freedman, a study sponsored by the United States National Highway Traffic Safety Administration (NHTSA)
- "Contributory Factors To Road Accidents" - Jonathan Mosedale, Andrew Purdy and Eddie Clarkson, a study by the United Kingdom Department for Transport
- "Keeping Eye and Mind on the Road" - Trent Victor, a study by the Uppsala University in Sweden.
NASA HUD Studies
The NASA Ames Research Center (in cooperation with San Jose State University and others) has conducted a number of studies concerning effectiveness and safety of head-up displays (HUDs). This research employed aircraft HUDs, but it is useful in evaluating the Virtual Cable™ HUD technology (the studies involved navigating airport taxiways and runways, focused on aspects shared by aircraft and automotive HUDs and employed test subjects with no aircraft pilot training).
Findings
Findings of these studies support the Virtual Cable™ interface design:
- HUD-based systems can be much safer
and much more intuitive in delivering navigational information than the
traditional displays; if and only if such
information is presented at least 8 degrees
from the out-the-window path being tracked. The best position for such information
is above such path.
In most driving situations, the Virtual Cable™ will be positioned at least 8 degrees above the path being followed.
- Making the HUD display non-distracting can
only be achieved by using conformal
(scene-linked) symbology. In other words, the
symbology must appear to the operator as a stationary part of the landscape.
The current HUD designs fix the position of the displayed image to the HUD itself.
When the operator is in motion, the symbology appears to be moving against the
outside landscape.
The Virtual Cable™ image is fully conformal (scene-linked); it appears to be a part of the landscape; it is stationary (fixed to the ground and not to the vehicle); and it is shown in true 3D (with primary depth cues present and in complete agreement). No other HUD technology known to us is capable of achieving such degree of conformality.
NOTE The primary depth cues present in the Virtual Cable™ image are: perspective, stereoscopic disparity, motion parallax, optic flow, convergence, focus and interposition. Providing the interposition depth cue in the Virtual Cable™ image is optional; and advantages and disadvantages of its presence are discussed in our patent applications.
If the Virtual Cable™ image was not shown in true 3D, it could not meet the first HUD design requirement (minimum 8-degree separation between the display symbology and the tracked path): without the primary depth cues being present, human vision would not be able to naturally correlate the Virtual Cable™ with the road; and the only other way to provide such correlation would be to overlay the road with the image of the Virtual Cable™, but that would provide 0 degrees of separation.
All of the applicable findings of these studies fully support the key principles behind the Virtual Cable™ interface design. All other commercial or experimental navigation systems known to us (HUD-based, map based, voice based, etc.) involve aspects of the human interface that have been proven distracting.
The following is a list of sudies that contain the findings summarized above. To help the reader, we have highlighted the most relevant parts of these reports. The original documents (without higlights) can be downloaded from the Human Factors Research & Technology Division, NASA Ames Research Center publications webpage.
- "HUD Symbology for Surface Operations: Command Guidance vs. Situation Guidance Formats" - Foyle, D.C., Hooey, B.L., Wilson, J.R., Johnson, W.A. (2002)
- "The Effect Of Visual Location On Cognitive Tunneling With Superimposed HUD Symbology" - Dowell, S.R., Foyle, D.C., Hooey, B.L., Williams, J.L. (2002)
- "Cognitive Tunneling In Head-up Display (HUD) Superimposed Symbology: Effects Of Information Location" - Foyle, D.C., Dowell, S.R. and Hooey, B.L. (2001)
- "Scene-linked Symbology to Improve Situation Awareness" - McCann, R. S., Foyle, D. C. (1995)
- "Attentional Issues With Superimposed Symbology: Formats For Scene-linked Displays" - Foyle, D.C., McCann, R.S. and Shelden, S.G. (1995)
- "Attentional Effects With Superimposed Symbology: Implications For Head-up Displays (HUD)" - Foyle, D.C., McCann, R.S., Sanford, B.D. and Schwirzke, M.F.J. (1993)
- "Attentional Issues in Superimposed Flight Symbology" - Foyle, D.C., Sanford, B.D. and McCann, R.S. (1991)